Full Schmidt characterization of spatiotemporally entangled states produced from spontaneous parametric down-conversion

Fuente: arXiv
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Main Authors: Pradhan, Rakesh, Kulkarni, Girish
Format: Preprint
Published: 2026
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author Pradhan, Rakesh
Kulkarni, Girish
author_facet Pradhan, Rakesh
Kulkarni, Girish
contents The full Schmidt decomposition of spatiotemporally entangled states generated from spontaneous parametric down-conversion (SPDC) has not been carried out until now due to the immense computational complexity arising from the large dimensionalities of the states. In this Letter, we utilize the rotational symmetry of the states to reduce the complexity by at least four orders of magnitude and carry out the decomposition to reveal the precise forms of the spatiotemporal Schmidt modes and the Schmidt spectrum spanning over 10^4 modes. We show that the Schmidt modes have a phase profile with a transverse spatial vortex structure that endows them with orbital angular momentum at all frequencies. In the high-gain regime, these Schmidt modes broaden and the Schmidt spectrum narrows with increasing pump strength. Our work can spur novel applications at the intersection of quantum imaging and spectroscopy that utilize entangled states produced from SPDC.
format Preprint
id arxiv_https___arxiv_org_abs_2602_07949
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Full Schmidt characterization of spatiotemporally entangled states produced from spontaneous parametric down-conversion
Pradhan, Rakesh
Kulkarni, Girish
Quantum Physics
Optics
The full Schmidt decomposition of spatiotemporally entangled states generated from spontaneous parametric down-conversion (SPDC) has not been carried out until now due to the immense computational complexity arising from the large dimensionalities of the states. In this Letter, we utilize the rotational symmetry of the states to reduce the complexity by at least four orders of magnitude and carry out the decomposition to reveal the precise forms of the spatiotemporal Schmidt modes and the Schmidt spectrum spanning over 10^4 modes. We show that the Schmidt modes have a phase profile with a transverse spatial vortex structure that endows them with orbital angular momentum at all frequencies. In the high-gain regime, these Schmidt modes broaden and the Schmidt spectrum narrows with increasing pump strength. Our work can spur novel applications at the intersection of quantum imaging and spectroscopy that utilize entangled states produced from SPDC.
title Full Schmidt characterization of spatiotemporally entangled states produced from spontaneous parametric down-conversion
topic Quantum Physics
Optics
url https://arxiv.org/abs/2602.07949